thanks just like to help as much as possible, omly dual core PC so two tasks it is

Cheers

No problem. Running more than one task per CPU would actually be counter-productive with all the internal CPU task switching from app to app, including cache flushes and reloads. What would be great is to do a single WU with multiple CPUs or cores, but an efficient way hasn't been found to do that yet as you run into other issues such as keeping each CPU/core updated as to what the other is doing, and not having each L2 cache per CPU/core duplicate the same data and trying to manipulate it at the same time.

I heard about a similar issues a few years ago reported here on the forums. As far as I know, it seems to be an anomaly that is not reproducible or explainable. Perhaps some strange branch in the BOINC code that is only encountered in rare situations, or some code messed up in memory due to a RAM glitch (which is actually caused by solar flares and why ECC memory was designed to prevent, as these errors happen roughly once a month per GB of RAM) causing a third app to be executed.

What I'd like to have explained is how I managed to have THREE WU's running, when I have a dual core CPU.

One of the three has recently completed, and there are now only two WU's running, as I was led to expect.

Anyone out there with an idea how this happened?

Three tasks is exactly right, one on each of the CPUs, one on the GPU. The GPU task uses a very small amount of CPU time, but so does the OS in managing display, file system, etc., etc.; that's the nature of multitasking operating systems. If you check Task Manager you'll probably find there are 40 or so processes getting some parts of the CPU time.

The fact that BOINC fails to have three tasks running if there's GPU work available should be what you're wondering about.

What I'd like to have explained is how I managed to have THREE WU's running, when I have a dual core CPU.

One of the three has recently completed, and there are now only two WU's running, as I was led to expect.

Anyone out there with an idea how this happened?

Three tasks is exactly right, one on each of the CPUs, one on the GPU. The GPU task uses a very small amount of CPU time, but so does the OS in managing display, file system, etc., etc.; that's the nature of multitasking operating systems. If you check Task Manager you'll probably find there are 40 or so processes getting some parts of the CPU time.

The fact that BOINC fails to have three tasks running if there's GPU work available should be what you're wondering about.

Joe

Hi Josef

I am running S@h and SETI Beta on the rig in question.
I had to re-attach it to both projects when I downloaded and installed BOINC 6.4.5

Initially, I attached to the main project, for a few WU's, to test things out.

One WU would run on one CPU core, the other on the GPU. "(0.05 CPU's 1 CUDA)" indicating the WU running on the GPU.

Having satisfied myself all was as it should be, I re-attached to the Beta project.

This produced a situation where the rig was crunching three WU's.

Once one of the three had finished, the situation changed, with one WU running on a CPU core, and 1 on the CUDA.

Reading other threads, I got the impression there should only be two WU's running on my rig. Please don't tell me it has installed wrongly! *sigh*

I heard about a similar issues a few years ago reported here on the forums. As far as I know, it seems to be an anomaly that is not reproducible or explainable. Perhaps some strange branch in the BOINC code that is only encountered in rare situations, or some code messed up in memory due to a RAM glitch (which is actually caused by solar flares and why ECC memory was designed to prevent, as these errors happen roughly once a month per GB of RAM) causing a third app to be executed.

Plenty of possibilities, but not many actual facts to work with.

Hi Ozz

I like your explanation! Thoughtful and written in non-technical English, it is succinct yet sufficiently ethereal to prevent the reader from understanding a word.

Initially, I attached to the main project, for a few WU's, to test things out.

One WU would run on one CPU core, the other on the GPU. "(0.05 CPU's 1 CUDA)" indicating the WU running on the GPU.

Having satisfied myself all was as it should be, I re-attached to the Beta project.

This produced a situation where the rig was crunching three WU's.

Once one of the three had finished, the situation changed, with one WU running on a CPU core, and 1 on the CUDA.

I have not used cuda but after reading a lot of posts about it my interpretation is this:

I believe it will not run two seperate tasks (for same project) on 1 core,
as in Task A = CUDA (using GPU + part CPU X to control GPU) and Task B = MB (using CPU X), only one task (A or B) at the same time.

However on your duo it will run 2 tasks for same project, as you have noted, 1 on each core, or 1 on core 1 + 1 on GPU (using core 2 to control GPU).

A second project is still able to use core 2 to run a task, giving a total of three tasks running.

You will only be able to get the third task running if the first two are from the same project.(EDIT... And 1 is on the GPU)

I do not have a CUDA compatible card so I canot confirm this, so if you are able to confirm/deny this hypothesis please post the result.

Initially, I attached to the main project, for a few WU's, to test things out.

One WU would run on one CPU core, the other on the GPU. "(0.05 CPU's 1 CUDA)" indicating the WU running on the GPU.

Having satisfied myself all was as it should be, I re-attached to the Beta project.

This produced a situation where the rig was crunching three WU's.

Once one of the three had finished, the situation changed, with one WU running on a CPU core, and 1 on the CUDA.

I have not used cuda but after reading a lot of posts about it my interpretation is this:

I believe it will not run two seperate tasks (for same project) on 1 core,
as in Task A = CUDA (using GPU + part CPU X to control GPU) and Task B = MB (using CPU X), only one task (A or B) at the same time.

However on your duo it will run 2 tasks for same project, as you have noted, 1 on each core, or 1 on core 1 + 1 on GPU (using core 2 to control GPU).

A second project is still able to use core 2 to run a task, giving a total of three tasks running.

You will only be able to get the third task running if the first two are from the same project.(EDIT... And 1 is on the GPU)

I do not have a CUDA compatible card so I canot confirm this, so if you are able to confirm/deny this hypothesis please post the result.

Substitute "application" for "project". Two AP and one MB CUDA should be supported, though BOINC 6.4.5 may leave a CPU essentially idle unless a cc_config.xml is used to encourage sensible usage.

It is possible to run 2 different WU's on one core: provided that they start on different cores... You go into Win Task Manager and "set affinity" for both WU's to the same core. I do this when backing up my computer, as (for reasons unknown to me) this speeds up the backup process by about 10-15x. On my quad-core, I run 4 WU's on 3 cores by excluding one core for the same reason..

Am I right in saying I need a third project (Say Einstein)so I can run that on one core, while the present two projects (applications) run on the second core and the GPU?

Errrr... No - you don't *NEED* a third project to use all cores. AstroPulse can keep all your cores busy while the GPU will do all the MB (i.e. Seti Enhanced) if you set up your machine as described in other threads in NC.

It is possible to run 5 wu at a time on a quaddie with a gpu (ie 4 cpu + 1 gpu), but you need to have a cc_config.xml with a <ncpus>5</ncpus> statement in it. By default it will run as 3+1. There is a "feeder" app that passes the data to the gpu and BOINC treats it as a task too, even though it only requires a small percentage of cpu time, which is why most of us use a cc_config.xml.

I believe there is more info on cc_config.xml in the FAQ's.

Hope this helps.

F.

[edit]Using the "Search forums" at the top of this thread for cc_config will turn up a lot more posts that may be useful to you. [/edit]

Much of it is above my head, as information I require seems to be assumed as obvious by the posters. This is very frustrating, as I'm sure you will understand. Having been away from the boards for several months, even the common abbreviation "MB" took a half hour of research to translate. (Multi-beam)

The default directories mentioned for locating the cc_config file do not exist on this PC. Is there something wrong with my BOINC installation? Is there something missing in the information I am reading?

What I am looking at now is:
2 x AP WU's. One is "Waiting to run"
The other is running.
A long list of CUDA WU's. One is running.
The rest are "Ready to start"

I understand why the CUDA apps are waiting to start, since there is only 1 GPU to process them.

What is stopping the second AP app from running?

I am continuing to search threads for a post written in English. *sigh*

I hope you didn't overwrite an existing file, not sure if you had to edit it and put that line in.
(I'm posting from a PSP, and haven't got a PC here with Boinc on to check).
Post in Number Crunching and someone will help.